Cutter head and knife



'May 29, 1928. L T. MEDHOLDT v1,671,600

Patented May 29, 1928.

UNI-reosIjAIE-s l.ifA.;*rif-.NI orpi-cn..

LOUIS '.r. MDIIOLDT, oF RoCKFoBL', ILLINOIS, Assloivon 'ro MATTIsoN MACHINE WORKS, or Rocxr'ort'n', ILLINOIS, A CORPORATION or ILLINOIS.

CUTTER HEA' AND KNIFE.

Application filed March 11, 1925. Serial Nb. 154,595.

This invention relates to cutterheads-such as aire used in mold'ersv and other Woodworking machines wherein a {lat-or contouredsurface is imparted to boards and strips fedthrough the machine.

- a clearance bevel. T'hesehevelsmay be from Ifrfr order that the corresponding' cutting edges of alll the knives sha/llv pass through precisely' the same orbit'- and` thus' operate -equally uponth'ef-'workand-so' produce-Chef desiredA smoothness,- it is neeessary','- 'securing the knivesin the cutter 2heafl as nearly in theI correct position'= as possible, to'subj'ect the-knivesito aise-called truing or j ointing. operation while th'eeu'tter head* is y rotating IatfullA speed. Y 'Ilhegtruin'g' or# jointing operation consists inwbriniging'la'- suitable abrasive element inlcontact Witli'lfhe' knives asthey are-revolving at full `As a; result of this operation the cutting' edges of all the-knivesaffre ground-'off slight-- ly until corresponding-edges' 0f" ali the knives travel atthe--same--distance-from the axis ofthe cutter head.v The jointir'igjfopera'-v tione changes the be'vel of. the! 'cuttingie'dgej narrow beveled approximate-ly 45. The surface. thus produced at the edge ofthe knife by the jointing is termed the heel.'

When as aresult ot repeated truingfor j'oin'tiing, the heel attains a Widthof' approx-imately one-thirty-second off an inch', th'eknives-must, in most eases` be removed from the cutter head and reground to restore't-hev original clearanceor cutting beveli and thus removethe heel. After thel'cnives have been resharpenedby theiabo've-or any other suitable method, t'h'ey are again secured in t-hel cutter head as accurately as practicable, and again trued or jointed as above' described.

To supplement the bolts ordinarily einployed inA securingcutter knives in place i'n the cut-ter head, one side of thek-ni'fe is some times provided with serrations tocoa'ct'! 4 with a similarly serrated surface onl ther-utfhv ter head or the securing. element.

It will Sucha: cutter head in various waysbe apparent thatl inv mount-ingl a set of sl'l'cli' serratedknives in the 'cutter head it is div cult,- ifA not impossible, to position all the: knives withtheir cutting edges projecting'- 'outwardly to the same extent, and conse-- quent-ly the jointing' may-produce an'- exces`- sively large heelupon one or more of the knives, the effect of which is tia-produce@ a non-uniform surface on thet-inisiiedWork.l

from; the cutter' h'ead fon-grinding to a new" clearance or cutting bevel will soon'-i become* necessary.

Among the salient objects ofthis iifvehl tion are to produce-a1 form of cutter inv which -theheel sli-ail 'never ex'ejeed"v tlie maximum widtlil which' can 'he tolerated, 'aifd tof lre'nd'er possible the: use o'fl expensivehighispeed steel'sor alloys Without-excessive':costlf blades of ordinary tool-steel, tlie1 thicknessA -of` the cutting-blade-being determin'edf,byv the-maa'iimum Width of"he'elf` which' caiifbe" successfully run on= the cutter, and s'adblades that it may be'- advanced fromV` timej to" time to compensate for Wear and' repeated truihg'or jointi'ng until the' cutter is Worn' out.

Inl the accompanying drawings, and? 2 are endviewsof two forms'off'cuttfe heads provided with knives-embodying the' features-off my invention. l

Fig. 3 is a perspective View of oiiiof-tli'e improved l'mive's.

Fig. 4 isa longitudinal sectional viewof tlie knife shown in Fig. '3.

Fig. 5 -is another form of the improved. knife. v

Fig. 6 is an end view of a cutter head in Which-the knife'shown in Fig. 5 mayl' employed:

Fig. 7 is a fraglnental elevation of'tli cutter head shownA in Fig. 6.

Fig. 8- is a. fragmentary sectionat View showing a pair ofvgibs supporting the' blade ina plain cylinder, the gib's'being'contouied to provide the backing forth'e blafde;

Referring first t'o the form of knife's'how in Figs.- 3- and 4:.

Said knife comprises a eutting'blade ll of high-speed steel or other suitable material and two supporting blades 2 and 3 of less expensive metal, the blade l being secured between the blades 2 and 3 by suitable means, as, for example, a screw 4. 'lhe edge of the cutting blade may be straight or of any desired contour. The adjacent ends of the supporting blades 2 and 3 are generally similar in form to the edge of the blade l. The supporting blades i?. and 3 are beveled to provide the necessary clearance. The blade 1 projects beyond the blades 2 and 3 a suitable distance, say, onesixteenth of an inch. The blades 2 and 3 extend near enough to the cutting edge of the blade l to support said blade 1 effectively during the cutting operation.

Cutterfhead knives constructed in accordance with the method disclosed in Figs. 3 and 4 .may be used in connection with cutter heads of various forms. In Fig. 1 I have shown a cylindrical cutter head A and in Fig. 2 a cutter head B of rectangular' crosssection, both adapted to receive knives embodying the present invention.

Most manufacturers are equipped with cutter heads in which the knives are secured in place by means of bolts a extending through open-end slots in the knives. The knife shown in Figs. 3 and 4 is provided with a slot 5 to receive such a bolt.

In Figs. 6 and 7 I have shown a cutter head C of the type wherein the cutting element is secured within a slot. in the body of the cutter head. Inasmuch as with a cutter head of this type, the cutting blade may be effectively supported without the use of blades such as those indicated at 2 and 3, I have shown a knife 7 in the form of a thin blade of high-speed steel. The cutterhead C is provided with a suitable number of slots 8 of a width corresponding to the thickness of the cutting blade 7. The latter is secured in place by means of a single gib 9 secured in a recess l0 at the forward side of the blade. respond generally to the contour of the cutting blade 7.

In F ig. 8 I have shown a cutter head D similar to the head C, but in this instance the body of the head is made plain and two blade supportinggibs 11 and 12 are provided. The outer edge portions of these gibs project beyond the periphery of the body and are contoured so as to provide the necessarv backing for the bla'de adjacent its cutting edge.

The thickness of the cutting element 1 or 7 is determined by the maximum width of heel that can be successfully run on a cutter, and in most instances would be approximately one thirty-second of an inch.

By means of the construction herein shown, it is unnecessary to remove the knives for grinding. When the cutting blades 1 or The head is contoured to cor- Y 7 require resharpening they are subjected to the truing or jointing operation, the cutter head being afterward adjusted toward the work to the necessary extent. Vhen as a result of repeated truing, the cutting edges of the blades l and 7 approach too close to the supporting blades 2 and 3 or gibs l1 and 12, (or to the body of the cutter head, in the form shown in Fig. (i) the cutting blades are loosened and adjusted outwardly to a suitable extent.

By reason of the small amount of highspeed steel employed, the first cost of a knife embodying the present invention is less than that of a cut-ter knife of the prior art. By obviating the necessity of removing the knives for grinding, I eil'ect an important saving in time. This saving is particularly great when serrated knivesare used, because of the difficulty of accurately positioning such knives in the cutter head.

It will be observed that the use of the thin cutting blade is rendered feasible by the provision in each instance of a backing for the blade adapt-ed to support it adjacent the cutting edge. When the cutting edge is of a special contour, as is usually the case, the outer edge or face of the backing provided is made of similar contour so as to support the blade uniformly along its cutting edge. The supporting blades such as shownA in Figs. 3 and 4, or the gibs l1 and l2, such as shown in Fig. 8 are especially suitable for relatively small manufacturers where frequent changes in the style or form of cutter must be made. In the case, however, of large manufacturers where a articular form or style of cutter is employed over long periods of time, in large quantity production, lthe body of the cutter head is preferably made of special contour to provide the necessary backing as shown in Fig. 6.

It will be apparent that due to the extreme lightness of the cutter blades, a measurable variation in the dimensions of a group of blades used in a cutter head will not seriously disturb the dynamic balance of the head.

It will also be apparent that the use of such thin blades will provide a cutter head in which the blades all have the same amount of heel and which, therefore, will produce finished work having a uniform surface.

I claim as my invention:

1. A cutting blade for the rotary cutter heads of molders and other Wood-cutting machines consisting of a thin blade of metal of a thickness not exceeding the maximum amount of heel that can be tolerated.

2. A cutting blade for the rotary cutter heads` of molders and other wood-cutting machines consisting of a thin blade of metal of a thickness not exceeding the maximum amount of heel that can be tolerated, and two supporting blades, one on each side of the cutting blade, all of said blades being rigidly and detachably connected together, the cutting edge of the cutting blade projecting a slight distance beyond the supporting blades and the latter being beveled at opposite sides of the cutting blade to provide clearance.

3. A rotary cutter head for molders and other wood working machines having a relatively thin cutting blade of a thickness not exceeding the maximum amount of heel that can be tolerated, and a pair of supporting members for the blade one on each side thereof, the cutting edge of the blade having a contour such that a plurality of points therein are variously located with respect to the axis of the cutter, and the outer edges of the supporting members being of similar contour but spaced a slight distance inwardly from the cutting edge of the blade.

4. A cutter head for molders and other Wood Working machines having a thin blade of a thickness not exceeding the maximum amount of heel that can be tolerated, and

a backing for said blade, the cutting edge of the blade being of a contour such that various points therein are located varying distances from the axis and said backing having a similar contour whereby to support the blade adjacent its cutting edge throughout the lengt-h thereof.

5. The combination of a cutting blade for molders and other Wood working machines, made from a thin piece of metal and having a cutting edge contoured to produce cuts of varying depth, and a rigid backing member for the blade adapted to be secured With the blade in a cutter head and having its outer edge of a contour conforming to the contour of the cutting edge of the blade, said outer edge of the backing member being disposed adjacent the cutting edge of the blade so as to prevent the latter from yielding in the cutting operation.

In testimony whereof, I have hereunto aflixed my signature.

LOUIS T. MEDHOLDT. 

